1. Field of the Invention
The present invention relates generally to load hoisting and handling apparatus and more particularly is directed to a coupling releasably attachable to an anchor affixed to a load, and to devices auxillary to such a coupler including a female to male anchor adapter and a void mold for setting anchors in poured concrete structures.
2. State of the Prior Art
Modern construction practices frequently require the lifting of massive bodies of cured concrete. For example, building walls may be cast at the construction site on a horizontal surface and then erected into position once the concrete is hardened and cured.
Considerable effort has been directed in the past to development of hoist coupling devices which would allow easy and safe attachment of the cable of a hoist to a concrete structural element with a simple, low cost but reliable coupling device. Such couplers are adapted to engage either an anchor embedded in the concrete piece or an element cast as part of the total concrete structure to be hoisted.
Exemplary of such prior art, is the device disclosed by Haeussler in U.S. Pat. No. 3,499,676. The Haeussler coupler is a hollow spheroidal one piece body which provides limited articulation i.e. degrees of free rotation of the concrete structure as it is being hoisted, and which is also somewhat difficult to engage with and release from the anchor because a twisting motion of the entire coupler body is required between the anchor receiving and releasing positions while the heavy hoist cable is attached to the coupler.
Somewhat improved devices are disclosed by Haeussler, et al., in U.S. Pat. No. 4,398,762, offering better articulation and greater ease of attachment but at the expense of structural complexity and which in any event differ substantially from the construction of the present invention in the approach taken to ensure safe operation.
Wood, et al., discloses a special purpose coupling mechanism engageable to an anchor fixed to a load which allows the coupler to be easily lowered onto the anchor for attachment thereto. The anchor is received within a hollow ball member which is rotated such that the anchor head is captured within a slot defined in the ball member. This coupler is essentially of two piece construction, namely a hollow ball rotatable within a housing and does not offer sufficient articulation for use in construction applications such as contemplated by the present applicant. The Wood device is especially designed for lifting and lowering radioactive fuel rods in nuclear reactors. The weight of these rods is known and sustantially constant. Most importantly, normal handling of the reactor fuel rods is predictable and limited to movements which do not impose substantial torsional or lateral forces on the coupler so that no positive capture of the anchor head within the hollow sphere is required and none is provided. Such a hoist coupler is not suited to handling the variety of loads encountered in construction applications nor does it offer sufficient articulation to allow manipulation and positioning of the load as it is hoisted into place in such construction applications.
Still other hoist coupling devices are disclosed by Truitt, et al., in U.S. Pat. No. 4,368,914 and Bochman, Jr. et al in U.S. Pat. No. 3,437,370. Both of these devices are far more complex than applicant's novel coupler disclosed herein. Still other couplers are disclosed by Bryant in U.S. Pat. No. 3,371,951 and Holt in U.S. Pat. No. 4,367,892 which however are intended for use with anchors different from those of the present invention.
A continuing need exists for hoist couplers offering greater ease of attachment and release, improved safety and reliability with a minimum of complexity and expense of manufacture.